[codex] Prepare v0.1.5 release

[Colvin-Y]

Summary

• bump Helm chart metadata and install examples to v0.1.5
• add CHANGELOG.md with diagnostic metadata and Helm provenance release notes
• include CHANGELOG.md and a packaged Helm chart archive in GitHub Release assets
• document kind-only release validation so local checks do not fall back to an ambient kubeconfig

Validation

• KUBECONFIG=/private/tmp/kubernetes-ontology-kind-kubeconfig GOCACHE=/private/tmp/kubernetes-ontology-go-build make ci
• kind live Pod diagnostic: asserted partial=true, diagnostic_budget_exceeded warning, truncated budgets, and rankedEvidence for bounded result
• kind live Pod diagnostic: asserted partial=false with non-empty nodes/edges/evidence for full budget
• kind live Workload diagnostic: asserted HelmRelease, HelmChart, managed_by_helm_release, installs_chart
• KUBECONFIG=/private/tmp/kubernetes-ontology-kind-kubeconfig helm package charts/kubernetes-ontology --destination /private/tmp/kubernetes-ontology-release-check
• KUBECONFIG=/private/tmp/kubernetes-ontology-kind-kubeconfig helm show chart /private/tmp/kubernetes-ontology-release-check/kubernetes-ontology-0.1.5.tgz
• git diff --check

Autoplan notes

• external Codex CLI review was requested with escalation and rejected by the safety policy as untrusted data export; no workaround was attempted
• local reviewer subtask completed and its concrete findings were incorporated
• all Kubernetes live checks used /private/tmp/kubernetes-ontology-kind-kubeconfig explicitly